The invention relates to the cooling of motor vehicles.
It relates more particularly to a cooling device of an electric vehicle powered by a fuel cell
Much work is currently being devoted to the development of fuel cells as sources of electrical energy for powering vehicles driven by electric motors.
It is known that a fuel cell transforms into electrical energy the chemical energy produced by a fuel-oxidant pair.
In the case of motor vehicles, the fuel cells which are currently proving to be the most promising are the cells of the membrane type, operating from a source of hydrogen originating either from a bottle carried on board the vehicle, or from a unit producing hydrogen directly in the vehicle. Hence it is possible to produce the hydrogen directly by using a reformer operating with an appropriate fuel, such as methanol, petrol, diesel oil, etc.
In a motor vehicle of the abovementioned type, it is necessary not only to cool the electric motor providing the propulsion of the vehicle as well as the power control for the said motor, but also the fuel cell itself, since the latter is generally supplied with hydrogen and air under pressure, which are usually at a temperature higher than ambient temperature.
The cooling of fuel cells poses certain problems given that it implies using de-ionised water as a cooling fluid. However, this cooling fluid exhibits several drawbacks. First of all, it is incompatible with various materials such as aluminium, copper or steel, for example. Moreover, this fluid freezes as soon as the temperature falls below 0xc2x0 C. And, needless to say, it is not possible to add antifreeze to this de-ionised water, as in the conventional circuits for cooling engines of motor vehicles.
The invention aims especially to provide a solution to the problems mentioned above.
According to one aspect of the present invention there is provided a cooling device for a vehicle with an electric motor powered by a fuel cell, the cooling device comprising a first cooling loop suitable for cooling the fuel cell and traversed by a first cooling fluid, a second cooling loop suitable for cooling at least the electric motor and traversed by a second cooling fluid, and a heat exchanger interposed between the first cooling loop and the second cooling loop.
Hence, the fuel cell and at least the electric motor are cooled by two loops using different cooling fluids and exchanging heat between them via an appropriate heat exchanger. That being so, the cooling of the fuel cell is carried out indirectly on the basis of the cooling fluid serving for cooling the motor.
Advantageously, the first cooling loop comprises thermal regulation means for keeping it in an ice-free condition.
These thermal regulation means advantageously comprise at least one electric heating resistance element integrated into a receptacle traversed by the first cooling fluid. This receptacle can be produced particularly in the form of a filling and outgassing vessel integrated into the first cooling loop.
Advantageously, the device further comprises means for thermal insulation of the first cooling loop.
The latter advantageously comprises an electric pump for putting the first cooling fluid into circulation.
In the invention, the second cooling loop advantageously comprises a cooling radiator traversed by the second cooling fluid and suitable for being swept by a flow of air.
According to another characteristic of the invention, the second cooling loop comprises a main branch incorporating the heat exchanger interposed between the first loop and the second loop, a secondary branch incorporating the cooling radiator and a thermostatic valve of the three-way type mounted at the junction of the main branch and of the secondary branch.
According to a further aspect of the invention there is provided a cooling device for a vehicle with an electric motor powered by a fuel cell, the cooling device comprising a first cooling loop suitable for cooling the fuel cell and traversed by a first cooling fluid, a second cooling loop suitable for cooling at least the electric motor and traversed by a second cooling fluid, and a heat exchanger interposed between the first cooling loop and the second cooling loop wherein the second cooling loop comprises a cooling radiator traversed by the second cooling fluid and suitable for being swept by a flow of air wherein the second cooling loop comprises a main branch incorporating the heat exchanger interposed between the first loop and the second loop, a secondary branch incorporating the cooling radiator and a thermostatic valve of the three-way type mounted at the junction of the main branch and of the secondary branch, wherein the second cooling loop moreover comprises a cooling element for cooling the electric motor of the vehicle.
When this electric motor is of the alternating-current type and is controlled by a power control, this cooling element advantageously serves for cooling both the electric motor and the power control.
The abovementioned cooling element may be incorporated either into the main branch of the second cooling loop, or into a diversion from this main branch.
It is advantageous for the second cooling loop further to comprise a heat exchanger for cooling at least one auxiliary unit of the fuel cell.
This heat exchanger may be incorporated into the secondary branch of the second cooling loop, or else into a diversion from the main branch of the second cooling loop.
The second cooling loop advantageously comprises a fan heater for heating the passenger compartment of the vehicle.
Moreover, this second cooling loop advantageously comprises an electric pump for putting the second cooling fluid into circulation.
The heat exchanger interposed between the first cooling loop and the second cooling loop is preferably produced essentially from stainless steel.